Authorities work to create vaccine for mosquito-borne Zika virus, believed to cause severe deformities in children

January 21, 20163:13pm

Little Jose Wesley, who is being held by his brother Elison at their home in Brazil, was born with microcephaly. Authorities believe there is a link between the mosquito-borne Zika virus and a surge of birth defects in Brazil. Picture: AP/Felipe Dana

FOR decades it was considered relatively harmless, only causing flu-like symptoms in some sufferers.

But now the Zika virus is believed to have a much more serious side effect, one that has authorities — even here in Australia — worried.

A recent outbreak of the infection in Brazil has been linked to the startling rise in the number of babies born with microcephaly, a disease that affects the development of the skull and brain.

Babies with the condition usually have a head two or three times smaller than average.

The virus is believed to be spread by a breed of mosquito found in Australia, making the prospect of an outbreak here a very real one.

According to Brazilian health authorities, there were more than 3500 reported cases of microcephaly last year compared to just 147 in 2014. The virus had also been linked to the deaths of 46 babies born with microcephaly in the country, The Washington Post reported.

In the US, three prgnant women in Florida and two in Illinois have tested positive, with all cases linked to travel to South America.

While experts say more tests need to be carried out to determine if the mosquito-borne virus directly causes the condition, the significant jump in cases prompted Brazil’s health ministry to declare a National Public Health Emergency. Twenty three out of 26 states have reported the presence of the Zika virus with the highest concentration in the northeastern part of Brazil.

In response, authorities set up a special taskforce to tackle the problem and tonnes of a biological agent that kills mosquito larvae was sent to affected areas.

The US Centers for Disease Control (CDC) has since issued a warning for pregnant women travelling to Brazil as well as 13 other countries where the Zika virus is known to be present, bolstering the belief the virus causes microcephaly.

And Australia’s Department of Foreign Affairs and Trade (DFAT) has also warned pregnant women travelling to Brazil to “exercise particular caution” following the outbreak saying it has been linked to causing babies to be born with “cognitive impairment”.

The Aedes aegypti mosquito is the carrier for the Zika virus, which has been linked to brain damage in babies. Picture: AP/Andre PennerSource:AP

So where did it all start?

The Zika virus was first detected in monkeys in the Zika Forest in Uganda in the late 1940s.

A decade later it appeared in humans mostly in west and central Africa but also occurs in Pakistan, India, Vietnam, Thailand, the Philippines, Malaysia, Indonesia and Micronesia.

For the next few decades it remained confined to those regions but recently began appearing in central and south America.

Now several cases have now been reported in the US with tests this week confirming two pregnant women in Illinois have contracted the virus.

How is it spread?

It is transmitted by the Aedes mosquito, which is also a carrier for yellow fever, dengue and the chikungunya virus. It is not spread through human-to-human contact.

This mosquito is found in almost all parts of the world, particularly tropical climates, making it a much bigger threat.

One of the main theories for the recent outbreak in Brazil was that it was transmitted by Asian soccer fans during the recent FIFA World Cup. The first case of the Zika virus was detected in May 2015. It has since spread rapidly with authorities now estimating about 1.5 million people have been infected.

What are the symptoms?

Symptoms are said to be similar to dengue fever, such as a mild fever, a rash, red eyes, conjunctivitis, headaches and muscles aches.

How serious is it?

Most people who contract the virus won’t suffer any symptoms making it harder to monitor.

Infectious disease expert Dr Sanjaya Senanayake from the Australian National University told news.com.au that until recently most health experts would have considered the Zika virus as relatively harmless, because of its flu-like symptoms.

Now, because of the birth defect issues, he said Brazilian authorities were advising women in some parts of the country to avoid getting pregnant.

“If you had asked me about the Zika virus two, three months ago about what it does I would have said that about three quarters of people who get Zika won’t even know they had it; they won’t even get symptoms,” he explained. “People are rarely hospitalised, no one dies from it but what has happened now since we have seen these big numbers in central and south America, and there have been some deaths linked to it.

“I think the big issue now is in northeastern Brazil where they have had a 20-fold increase in the number of pregnant women or women giving birth to babies with microcephaly.

“They have tried to work out what was going on and they haven’t been able to find any other explanation apart from the fact that there’s a lot more Zika around and they even found the Zika virus in foetuses with the microcephaly birth defect. It’s not a definite association but it is looking very likely and there is no alternate explanation.

A specialist fumigates the Nueva Esperanza graveyard in the outskirts of Lima to prevent the spread of the Chikunguya and Zika virus, which affect several South American countries. Picture: AFP/Ernesto BenavidesSource:AFP

Is there a cure or vaccine?

No, because it was considered a low-level threat. The best way to protect yourself from the disease in stay clear of areas where it occurs and use preventive measures such as wearing repellents.

However the US has begun the process to develop a vaccine following the outbreak in Brazil and the links to microcephaly.

The Brazilian government has announced it will direct funds to a biomedical research centre to help develop a vaccine against the Zika virus linked to brain damage in babies.

What is microcephaly?

Microcephaly is a condition that describes a smaller-than-normal-sized head because the brain has not developed properly or has stopped growing. Microcephaly can be present at birth or it may develop in the first few years of life.

It occurs during foetal development if the mother abused drugs or alcohol, became infected with a cytomegalovirus, rubella (German measles) or varicella (chickenpox) virus, was exposed to certain toxic chemicals, or had untreated phenylketonuria (PKU).

Now there is strong evidence to suggest the Zika virus also causes it.

Is it a threat to Australia?

Dr Senanayake told news.com.au the threat was low but there was a potential for an outbreak to occur.

He said the Aedes mosquito was found in far-north Queensland, and the Cairns region was known to have outbreaks of dengue fever.

“So, the risk for Australia would be if we had lots of travellers returning to Cairns with Zika virus in their blood and the local Cairns Aedes mosquitoes taking a bite from them while they have the virus in their blood,” he said. “It only causes a flu-like illness but if you are pregnant then you are at an increased risk of these birth defects. That is obviously then a very serious matter.”

Queensland Health have issued an alert about a Zika virus risk in tropical areas of the state, but there was so far no evidence of the virus in Queensland.

Dr Senanayake said another concern is for Australians travelling to Rio de Janeiro for this year’s Olympics.

While most of the Zika outbreak is in the northeastern part of the country, it has also been detected in Rio.

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